The present invention relates generally to automated tooling, and pertains more particularly to a versatile input/output control and power distribution block for use with automated tooling.
When using automated tooling, a programmable logic controller or computer is often required to send output control signals to, and receive input sensor signals from, a number of automated tools. Typically the connection to each automated tool consists of three wires: a wire which carries a ground signal, a wire which carries a power signal, and a wire which carries an input/output (I/O) signal which either is a control signal that is output from the controller to the automated tool, or a sensor signal from the automated tool that is input to the controller.
The connections from the automated tools are typically terminated at a termination block. At the termination block, the ground signals and the power signals connected to the automated tools are combined respectively. The termination block passes the control signals and the sensor signals between the programmable logic controller or computer and the individual automated tools.
The three individual wires from each automated tool sensor or control, grouped together in a cable, have typically been connected to a terminator block using wire leads held in individual wire receptacles. However, when automation tools are used in production, this mechanical arrangement frequently results in the sensor cables being subject to repetitive motion. Over the course of time, this can result in the wires within the cables becoming intermittently or permanently defective. In addition, replacement of I/O cables with wire leads held in individual wire receptacles can be time consuming.
To alleviate this problem, some manufacturers have utilized I/O cables with connectors which can be plugged into a termination block. This has provided for an easier replacement of defective cables. However, existing units which utilize these types of connectors typically can connect to no more than eight I/O connector cables, and are not backward compatible with automated tools which require the use of pull-up/down resistors or which have wires with flying leads.
In addition, programmable logic controllers typically provide a number of input/output lines, frequently sixteen, packaged in a single I/O module. As a result, it would be most efficient to connect a single I/O cable from the controller to a termination block of the corresponding size. However, it is not infrequent that an automated tool occupies a relatively large physical area, such as a number of different bays of equipment, with clusters of input/output connections of fewer than sixteen lines spaced dozens or even hundreds of feet away from each other. As a result, in order to make full use of all the lines in the controller""s I/O module, a number of separate wires will need to run a relatively long distance to the proper area of the tool. It would be a far more robust arrangement with more optimal interconnect wiring the appropriate I/O connections could be provided in the desired areas of the tool, while still allowing simple and reliable cabling from the controller to the termination block.
In a preferred embodiment, the present invention provides a modular, distributable termination system for an automated tooling arrangement that is easy to wire and physically robust. The termination system has at least one chainable termination puck with at least one termination connector which provides a total of (L) local signal lines for connection to I/O devices of the automated tooling. The puck also has an I/O-side chaining connector with a total of (Nxe2x88x92L) remote signal lines, and a PLC-side chaining connector with a total of (N) lines which is electrically connected to the (L) local signal lines and the (Nxe2x88x92L) remote signal lines. The signals are arranged on the two chaining connectors such that the remote signal lines are shifted in position on the PLC-side chaining connector relative to the I/O-side chaining connector by the number (L) of local signal lines, and replaced in position by the local signal lines. In the preferred embodiment, N=16, and L=2, 4, or 8. The I/O-side chaining connector of one chainable termination puck is electrically engageable with the PLC-side chaining connector of an additional chainable termination puck, thus providing the desired modularity in terms of the number of I/O connections. The two chaining connectors are complementary such that they can be mechanically mated with each other when additional I/O points are required in the same area, or they can be connected using an electrical cable assembly so that the I/O points can be distributed to the areas of the tool that require them. In the preferred embodiment, the termination connector is a DIN connector, while the two chaining connectors are the same type of connector having the same number of pins but a different gender, typically mail and female 25 pin female D-sub connectors. The puck also has power and ground lines on the first and second chaining connectors and the termination connectors which are used to supply power from the controller to I/O devices connected to the termination connectors.
An alternate embodiment of the termination system includes a termination block puck which has two chaining connectors and multiple I/O device connectors, of a type different from the termination connectors. The termination block puck also has multiple switches for selecting either a line from the chaining connector or a line from one of the I/O device connectors to be electrically connected to a line of the second main connector.
The present invention may also be implemented as a method for distributing a linearly ordered group of input/output lines from a controller to input/output devices. Such a method includes receiving a first linearly ordered group, connecting the lines in a local subgroup adjacent a first end of the first linearly ordered group to at least one termination connector, shifting the lines in a remote subgroup comprising the remaining input/output lines in a direction toward the first end so as to form a second linearly ordered group, and providing the second linearly ordered group to an external device. Both linearly ordered groups have the same number of lines. Some embodiments further include electrically connecting the first termination puck to the controller, and electrically connecting the first termination puck to a second termination puck. The first linearly ordered group can be received at a PLC-side connector adapted for connection to the controller, and the second linearly ordered group can be provided to an I/O-side connector adapted for connection to the second termination puck. Since the second linearly ordered group has more lines than the remote subgroup, no connections are made to the extra lines in the second group.